Oil and gas production from unconsolidated/weakly-consolidated sands requires a production screen in the hole to inhibit the movement of formation sand and keep the hole open. For open hole completions where the sand control screen directly retains the formation sand, proper screen selection is necessary to provide optimum life and minimum sand passing. Several screen sizing selection criteria are available in the literature such as Saucier, Coberly, Schwartz and others. However, these rules may not always be applicable, especially when premium screens, with metal meshes are used. These screens may use multi layers of wire mesh and its complex shaped pore opening may result in retention performance quite different from wire wrap screen slots. Experimental work has been done on a very fine (d50=115–130 µm) uniform (uniformity coefficient=d40/d90=3) and a non-uniform (uniformity coefficient=ca 7) sands on a series of commercial screens segments. These screens include standard wire wrap and also premium grade screens. The testing consisted of pressure drop measurements and sand retention while the screen is subjected to a fluidized stream of sand. Analysis of the data provides a method of measuring screen performance during and after filter cake bridging/building. Utilizing this data, screen performance, i.e. comparative lifetime and sand passing can be projected based on a maximum a pressure drop across the screen assembly. This analysis method is applicable for any type of screen and formation. Where possible, the results from the experimental tests are compared to prior literature screen selection methods. Graphs of the normalized data allow for a logical selection of the appropriate screen for a given formation sand. Technical Contribution:A new procedure for the selection of production screens applicable to any formationA comparison of the new method with prior literature methodsA comparison of performance of wire wrapped screens and premium screens. Introduction Open hole completions in oil/gas wells have been common practice for the past several years. These wells have generally been long horizontal wells. The many problems and difficulties to get successful completions has been well documented, as many operators have been disappointed with the results. It is now recognized that a successful horizontal open hole completion requires careful analysis of many factors. These are often dependent variables since a selection of a technology or method for either the drilling or completion may limit the use to only a few other interrelated products and services. One of the key factors is to evaluate what type of screen technology may be necessary for sand control. The reservoir conditions usually dictate whether sand control is needed and greatly influence whether the applied technology can be successful. When direct retention of reservoir sands is the likely completion scenario, a good understanding of the capabilities of the various types of screen technology is required. This includes the screen's capabilities to retain the formation sands, and its sensitivity to drill-in-solids based on the optimum drilling fluids, and well completion cleaning additives and methods that may be utilized.

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Electron spin resonance has been recently applied to the study of adsorbed surfactant structures in aqueous solution. The extension of this technique to apolar media requires an accurate understanding of the absorption behavior of the nitroxide probes used in this type of investigation and of their interactions with the adsorbed species. In this study, adsorption on alumina in cyclohexane was carried out for two types of nitroxide probes: Tempo derivatives (hydroxy and amino) and n-doxylstearic acids ( = 5, 7,12, 16).All probes were found to adsorb on the mineral surface, but the addition of a surfactant, Aerosol OT, was found to affect the probe adsorption significantly. While the adsorbed layer of Aerosol OT solubilized the Tempo probes, it did not affect the adsorption of the 5-and 7-doxylstearic acids. Importantly, the molecular configuration of the 12-and 16-doxylstearic was found to be highly sensitive to the amount of surfactant adsorbed on the mineral. It is suggested that the configuration of these probes depends upon the surface pressure developed on the solid surface by the adsorbed surfactant species.

A few cased-hole gas wells in Southeast Asia that were initially completed without any sand control are now producing sand, and the operators want to remediate these wells via standalone sand screen inside the production tubing. In these wells, the fluid (gas/sand) produced through the perforations would impinge rather directly on the screen, and erosion of the screens could be one of the major concerns. Therefore, a project was undertaken with the main objective of comparing the gas-erosion resistance and sand control efficiency of different types of sand screens via laboratory experiments. The results demonstrate that the erosion resistance was dependent on the screen type, gas velocity, and particle size distribution of the abrasive media (sand). Poorly sorted sand with more fines exhibited more damage than well sorted uniform sand, emphasizing the importance of right sizing of sand to minimize screen damage. The erosion lifetime of the screens was ranked as: bead screen > mesh screen > wire-wrapped screen. The time to failure for the bead screen was at least 2.5 times higher than the premium mesh screen protected by a louvered shroud, while the wire wrap screens only lasted a fraction of time before losing its sand retention capacity. However, sand plugging was found to be a concern for the bead screen, suggesting that it must be behind another primary sand control such as gravel packing to protect it against plugging, and would be very effective fail-safe sand control device under such configuration. The louver design shroud protecting the mesh screen proved to be ideal for sand producing gas wells due to its moderate erosion resistance, low concerns due to sand plugging, and high sand control efficiency.